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United States Patent |
5,762,237
|
Chang
|
June 9, 1998
|
Cartridge lock for caulk dispensing devices
Abstract
A simple, inexpensive and efficient cartridge lock to retain a caulk
cartridge within the frame of a caulk gun until intentionally released by
the operator, thereby eliminating a potential safety hazard. The cartridge
lock includes a resilient spacer having a central passage for slidable
insertion over the plunger shaft of the caulk gun. The spacer is inserted
onto the plunger shaft and is carried thereon between the piston and
supporting wall to require an additional measure of force for retraction
of the plunger shaft in order to insert a new cartridge or remove an old
one. This avoids inadvertent release and fall-through of the cartridge.
Various embodiments of the spacer are contemplated including a constricted
spring having one end formed with coils sized for slidable insertion over
the plunger shaft, and a constricted end formed with at least one tighter
coil for gripping the plunger shaft. The constricted spring is inserted
onto the plunger shaft and is carried thereon between the piston and
supporting wall. Alternatively, the resilient spacer may be a length of
resilient material formed in an arc and having a central through-bore for
insertion on the plunger shaft.
Inventors:
|
Chang; Peter J. (11001 Petersborough Dr., Rockville, MD 20852)
|
Appl. No.:
|
597263 |
Filed:
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February 6, 1996 |
Current U.S. Class: |
222/153.09; 222/327 |
Intern'l Class: |
B67B 005/32 |
Field of Search: |
222/326,327,340,153.09,391
|
References Cited
U.S. Patent Documents
1986166 | Jan., 1935 | Schneider | 222/340.
|
3381861 | May., 1968 | Stein | 222/327.
|
4204616 | May., 1980 | Chang | 222/391.
|
5336014 | Aug., 1994 | Keller | 222/327.
|
Primary Examiner: Huson; Gregory L.
Attorney, Agent or Firm: Law Offices of Royal W. Craig
Claims
I claim:
1. An improvement for a dispensing gun having a frame extending forwardly
of a supporting wall and adapted to receive a replaceable cartridge, and a
piston distally mounted on a plunger shaft and drivable through said frame
and cartridge for dispensing contents of the latter, the improvement
comprising:
a constricted spring having one end formed with coils sized for insertion
over said plunger shaft, and a constricted end formed with at least one
tighter coil for frictionally gripping said plunger shaft, said
constricted spring encircling said plunger shaft forwardly of said
supporting wall;
whereby said constricted spring serves as a resilient spacer between said
piston and said supporting wall and requires an additional measure of
force for retraction of said plunger shaft in order to insert or remove a
said replaceable cartridge.
2. The improvement for a dispensing gun according to claim 1, wherein said
constricted spring is carried on said plunger shaft behind said piston.
3. The improvement for a dispensing gun according to claim 1, wherein said
constricted spring is attached to said supporting wall and encircles said
plunger shaft in advance thereof.
4. The improvement for a dispensing gun according to claim 1, wherein said
at least one tighter coil of said constricted spring frictionally grips
said plunger shaft, said spring frictionally riding said plunger shaft
between said piston and supporting wall.
5. The improvement for a dispensing gun according to claim 1, wherein said
plunger shaft includes a threaded protrusion extending from a distal end
to allow said piston to be secured thereto by a nut, and said constricted
spring includes at least one coil constricted to conform to said threaded
protrusion, said constricted spring being inserted over said plunger shaft
with said at least one coil seated around said threaded protrusion,
whereby a severed end of said constricted spring bites the plunger shaft
and acts as a lock washer when sandwiched by said piston.
6. An improvement for a dispensing gun having a frame extending forwardly
of a supporting wall and adapted to receive a replaceable cartridge, and a
piston distally mounted on a plunger shaft and drivable through said frame
and cartridge for dispensing contents of the latter, the improvement
comprising:
a resilient spacer having a central through-bore for slidable insertion
over said plunger shaft, said through-bore being sized for frictionally
gripping said plunger shaft, said spacer being carried by said plunger
shaft between said piston and supporting wall;
whereby said resilient spacer is interposed between said piston and said
supporting wall to require an additional measure of force for frictional
retraction of said plunger shaft through the through-bore of said spacer
in order to insert or remove a said replaceable cartridge.
7. The improvement for a dispensing gun according to claim 6, wherein said
resilient spacer is carried on said plunger shaft behind said piston.
8. The improvement for a dispensing gun according to claim 6, wherein said
resilient spacer is attached to said supporting wall.
9. The improvement for a dispensing gun according to claim 6, wherein said
resilient spacer comprises a section of resilient material formed with an
arc, and said central through-bore is centered in said arc.
10. The improvement for a dispensing gun according to claim 9, wherein said
resilient spacer includes opposing ends flared outwardly from said arc
along a common plane, said flared ends serving as flat bearing surfaces
when compressed against said supporting wall.
Description
FIELD OF THE INVENTION
The present invention relates to dispensing devices and, more particularly,
to hand-held caulk guns for ejecting caulk compound from a disposable
cartridge.
BACKGROUND OF THE INVENTION
Conventional economy brand caulking guns are generally manual
trigger-operated devices incorporating a unidirectional gripping assembly
which urges a piston rod forward to eject the compound from a cartridge.
One such prior art caulk gun is set forth in FIG. 1. This is a
lightweight, skeleton-frame caulking gun designed to receive and carry a
disposable caulk cartridge 20. Unfortunately, this skeleton-frame gun
presents serious safety problems in loading and unloading the cartridge
20. Loading can be somewhat awkward and, depending on whether the user is
left-handed or right-handed, takes place from the left or right. The
operator only has two hands; one holds the cartridge and the other holds
the caulking gun at the handle. Just a moment's carelessness or
distraction of the operator may cause the pointed end or nozzle 20' of the
cartridge to miss when thrust at the opening 26'. When the hand holding
the cartridge 20 is shifted to line up the rear with the plunger, the
cartridge will inadvertently fall through the open frame onto whatever may
be below, point down. Typically, the user tilts the gun for better access,
thereby increasing the danger of dropping the cartridge through the frame.
Even when dropped on the foot a loaded cartridge can produce injury. When
dropped from a scaffolding or ladder the lethal potential of the sharp
point is evident.
When the cartridge is empty and in need of replacement, the plunger is
retracted all the way. Once the piston is removed from within the caulk
cartridge, the cartridge 20 becomes free to fall out of the barrel. Again,
a serious safety threat is posed during unloading.
U.S. Pat. No. 4,204,616 issued to the inventor named herein for his
"Adjustable Safety Guide for Skeleton Type Caulking Gun" is an attempt to
solve the above-described problems. This patented gun (shown in FIG. 2)
includes a flexible-panel guard 32 (which may be canvas or other
lightweight sheeting) secured along the barrel arms of the caulking gun.
Enough slack is provided for the guard to fit as a half-sleeve around one
side of a standard size cartridge installed in the caulking gun. The
cartridge can be installed from either side. The guard automatically
alleviates the cartridge drop-through hazard during loading regardless of
from which side of the caulking gun the cartridge is inserted. The guard
also helps during unloading since the empty cartridge is partially
supported after the piston is retracted. However, the guard has a few
drawbacks. For instance, it is labor-intensive and relatively expensive to
manufacture and install. In addition, compound often spills over onto the
guard and it becomes messy and hard to use, especially if it hardens. This
can shorten the useful life of the gun.
It would be greatly advantageous to provide a more economical safety lock
for retaining a caulk cartridge within the barrel arms during loading
until intentionally unlocked by the operator.
SUMMARY OF THE INVENTION
In accordance with the above, it is an object of the present invention to
provide a simple, inexpensive and efficient cartridge locking mechanism to
retain a caulk cartridge within the frame of a caulk gun until
intentionally released by the operator, thereby eliminating a potential
safety hazard.
It is a further object to provide a safety lock as described above which is
easy to use by either right-handed or left-handed users.
The above and other objects and advantages of the invention will become
more readily apparent on examination of the following description,
including the drawings, in which like reference numerals refer to like
parts. For the purpose of illustration, the cartridge-lock is shown in the
context of skeleton-frame caulking gun of the type having a metal or
single piece molded plastic open frame secured to a supporting wall and
extending forwardly therefrom. A thrust mechanism is supported in a
housing behind the supporting wall and is actuated by a downwardly
extending trigger to drive a plunger shaft that is slidably supported in
the housing. A piston is mounted on the distal end of the plunger shaft
and, when advanced through the frame and cartridge, dispenses caulking
composition from the cartridge. As will be seen, the cartridge-lock must
be used with an open front support for supporting the nozzle of the
cartridge. A closed front support would block proper insertion of the
cartridge.
The improvement disclosed herein includes a cartridge-lock comprising a
resilient spacer having a central passage for slidable insertion over the
plunger shaft. The spacer is inserted onto the plunger shaft and is
carried thereon between the piston and supporting wall. The resilient
spacer is interposed between the piston and supporting wall to require an
additional measure of force for retraction of the plunger shaft in order
to insert a new cartridge or remove an old one.
In one embodiment, the resilient spacer is a constricted spring having one
end formed with coils sized for slidable insertion over the plunger shaft,
and a constricted end formed with at least one tighter coil for gripping
the plunger shaft. The constricted spring is inserted onto the plunger
shaft and is carried thereon between the piston and supporting wall.
In another embodiment, the resilient spacer is a length of resilient
material formed in an arc and having a central through-bore for insertion
on the plunger shaft.
In these and other embodiments, the resilient spacer is interposed between
the piston and supporting wall to require an additional measure of force
for full retraction of the plunger shaft in order to insert a new
cartridge or remove an old one.
All of the subsequently described cartridge lock assemblies avoid
inadvertent release and fall-through of the cartridge. They are simple and
inexpensive to manufacture, yet highly effective. Their simplicity allows
them to be manufactured OEM or retrofit for minimal additional cost.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a side elevational view of a prior art skeleton-frame gun showing
the problem of loading;
FIG. 2 is a side elevational view of a prior art attempt to solve the
above-described loading problem as set forth in U.S. Pat. No. 4,204,616
issued to the inventor named herein for his "Adjustable Safety Guide for
Skeleton Type Caulking Gun".
FIG. 3 is a side elevational view of one embodiment of the cartridge lock
according to one embodiment of the present invention.
FIG. 4 is a side assembly drawing of the embodiment of FIG. 3.
FIG. 5 is a side perspective view of the assembled cartridge lock of FIG.
3.
FIG. 6 is a side assembly drawing of another embodiment of the cartridge
lock.
FIG. 7 is a side perspective view of the assembled cartridge lock of FIG.
6.
FIG. 8 is a side elevational view of the cartridge lock of FIGS. 6 and 7.
FIG. 9 is a side elevation view of another embodiment of the cartridge lock
similar to that as shown in FIG. 3, except that the constricted spring 100
is attached to supporting wall 33.
FIG. 10 is a side elevation view of another embodiment of the cartridge
lock similar to that as shown in FIG. 6, except that the resilient section
200 is attached to supporting wall 33.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a side elevational view of a prior art skeleton-frame gun showing
the problem of loading. This open-frame skeleton gun incorporates a
forward frame with two opposing arms 22 and 24 extending between a
supporting wall 33 and a forward support yoke 26. The illustrated frame is
adapted for carrying a conventional replaceable caulk cartridge 20 which
may be inserted in advance of supporting wall 33 with its nozzle cradled
in support yoke 26.
A piston 28 is mounted at the distal end of a plunger shaft 14. A thrust
assembly effects forward operation of the plunger shaft 14 and piston 28.
The thrust assembly is actuated by a trigger that is retracted by hand to
urge a grip forward. As the grip is biased forward it reaches a critical
angle where it engages plunger shaft 14, and further retraction of the
trigger is converted into lateral movement of plunger drive shaft 14. The
plunger drive shaft 14 urges piston 28 incrementally forward through
cartridge 20 in order to expel its contents.
When the cartridge is empty and in need of replacement, a rearward release
lever is depressed to free the plunger shaft 14, and plunger shaft 14 is
retracted. Plunger shaft 14 must be fully retracted to remove the
cartridge otherwise the presence of the piston 28 inside the cartridge
anchors it within the frame. Once the piston clears the interior confines
of the caulk cartridge, the cartridge 20 becomes unconstrained and is free
to fall out of the frame. There is no way for the user to gauge when the
cartridge 20 will fall free. This presents a serious safety threat during
unloading, especially if the gun is being operated on top of a ladder.
FIG. 2 shows a partial solution as set forth in U.S. Pat. No. 4,204,616
issued to the inventor named herein for his "Adjustable Safety Guide for
Skeleton Type Caulking Gun". This gun includes a flexible-panel guard 32
formed of canvas, Mylar, or other lightweight sheeting. The guard 32 is
secured along the opposing arms 22, 24 of the frame. Enough slack is
provided for the guard to fit as a half-sleeve around one side of a
standard size cartridge installed in the gun. Guard 32 prevents cartridge
drop-through during loading and helps during unloading since the empty
cartridge is at least partially supported after the piston is retracted
therefrom. However, guard 32 is labor-intensive and relatively expensive
to manufacture and install. In addition, caulk or other compound often
spills over onto the guard 32 and it becomes messy and hard to use,
especially if the compound hardens. This can shorten the useful life of
the gun.
FIG. 3 is a side elevational view of one embodiment of a cartridge lock
according to the present invention. The cartridge lock here comprises a
constricted spring 100 that is preferably formed with progressively
constricted coils from any suitable resilient material such as high carbon
spring steel. Constricted spring 100 has one larger end formed with coils
sized for free insertion over plunger shaft 14, and a constricted end
formed with at least one tighter coil for gripping the plunger shaft 14.
The constricted spring 100 is inserted onto the plunger shaft 14 and is
carried thereon at any point between the piston 28 and supporting wall 33.
Although constricted spring 100 is shown proximate the piston 28, it may
also be positioned near or attached to supporting wall 33 as shown in FIG.
9.
The constricted spring 100 serves as a resilient spacer between the piston
28 and supporting wall 33. When the plunger shaft 14 is retracted for
insertion/replacement of a cartridge, constricted spring 100 requires an
additional measure of force for full retraction. This ensures that the
piston 28 does not clear the confines of the cartridge until intended by
the user. The user can feel when the piston 28 is about to clear the
cartridge, and can consciously and carefully withdraw the piston 20
against the additional bias imparted by constricted spring 100. This
serves as a simple, inexpensive and efficient cartridge locking mechanism
for retaining the cartridge within the frame of the caulk gun until
intentionally and fully released by the user. This helps to eliminate the
potential safety hazard of inadvertent fall-through. The safety lock
described above is automatic and easy to use by both right-handed or
left-handed users.
It is noteworthy the cartridge-lock of the present invention compels the
use of an open forward support yoke 26 for supporting the nozzle of the
cartridge (e.g., one having an insertion slot for the cartridge nozzle as
shown). Since the rear of the cartridge must be inserted into the frame
first, a closed front support would block insertion.
FIG. 4 is an enlarged side assembly drawing of the embodiment of FIG. 3. A
threaded protrusion extends from the distal end of plunger shaft 14 to
allow piston 28 to be secured thereto by means of a conventional nut 35 or
other securing means. Piston 28 is inserted in advance of the nut 35. The
larger coils of spring 100 are sized to fit freely over plunger shaft 14.
At least one coil of spring 100 is constricted to a point where its outer
diameter conforms to the plunger shaft 14 and frictionally grips shaft 14.
The present invention is intended to encompass a spring 100 that is free
to slide along plunger shaft 14 between piston 28 and supporting wall 33,
and secured only by the friction of its constricted coil(s). However, it
has been found that constricted spring 100 can serve the dual purpose of a
lock washer for securing nut 35 onto the threaded protrusion of plunger
shaft 14. This is accomplished by forming at least one coil of spring 100
so that it is constricted to a point where its outer diameter conforms to
the threaded protrusion of plunger shaft 14. This way, as shown in the
assembled drawing of FIG. 5, when the constricted coil(s) of spring 100
are seated on the threaded protrusion, they become sandwiched between the
larger section of plunger rod 14 and piston 28. When nut 35 is tightened,
the severed end of spring 100 bites the plunger rod 14 and acts as a lock
washer.
FIG. 6 is a side assembly drawing of another embodiment of the cartridge
lock according to the present invention. The cartridge lock here comprises
a section 200 of resilient material such as high-carbon spring steel that
is preferably formed with an arc. Section 200 is further defined by a
central through-bore sized for free insertion over plunger shaft 14.
FIG. 7 is a side perspective view of the assembled cartridge lock of FIG.
6. The resilient section 200 is inserted onto the plunger shaft 14 and is
carried thereon at any point between the piston 28 and supporting wall 33
as shown in FIG. 9, here arching backward toward supporting wall 33.
Again, section 200 serves as a resilient spacer between the piston 28 and
supporting wall 33, and although proximate the piston 28, it may also be
positioned near or attached to supporting wall 33 as shown in FIG. 10.
When the plunger shaft 14 is retracted for insertion/replacement of a
cartridge, resilient section 200 becomes compressed between the piston 28
and supporting wall and requires an additional measure of force for full
retraction. This ensures that the piston 28 does not clear the confines of
the cartridge until intended by the user. The user can feel the additional
bias when the piston 28 is about to clear the cartridge, and can
consciously and carefully withdraw the piston 20 to overcome the
additional bias imparted by resilient section 200. This likewise serves as
a simple, inexpensive and efficient cartridge locking mechanism for
retaining the cartridge within the frame of the caulk gun until
intentionally and fully released by the user, thereby eliminating the
potential safety hazard of inadvertent fall-through.
FIG. 8 is a side elevational view of the resilient section 200 of FIGS. 6
and 7. Resilient section 200 may be formed from a strip of resilient
high-carbon spring steel that is bent to have an arcuate mid-section.
Preferably, the ends of resilient section 200 are flared outwardly along a
vertical plane to provide flat bearing surfaces against supporting wall
33. A central through bore is formed in the mid-section of resilient
section 200 for insertion onto plunger shaft 14.
Again, it is intended that the resilient section 200 may be free to slide
along plunger shaft 14 between piston 28 and supporting wall 33. However,
resilient section 200 may serve the dual purpose of a washer in securing
nut 35 onto the threaded protrusion of plunger shaft 14. This is
accomplished by sizing the central through-bore to a point where its
diameter conforms to the threaded protrusion of plunger shaft 14. This
way, as shown in the assembled drawing of FIG. 7, when the resilient
section 200 is seated on the threaded protrusion, it becomes sandwiched
between the larger section of plunger rod 14 and piston 28. When nut 35 is
tightened, the resilient section 200 acts as a washer.
Having now fully set forth a detailed example and certain modifications
incorporating the concept underlying the present invention, various other
modifications will obviously occur to those skilled in the art upon
becoming familiar with said underlying concept. It is to be understood,
therefore, that within the scope of the appended claims, the invention may
be practiced otherwise than as specifically set forth herein.
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